================================================================== BUG: KASAN: use-after-free in l2cap_chan_close+0x564/0xb10 net/bluetooth/l2cap_core.c:794 Read of size 1 at addr ffff888040441020 by task kworker/0:7/3844 CPU: 0 PID: 3844 Comm: kworker/0:7 Not tainted 5.8.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events do_enable_set Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 l2cap_chan_close+0x564/0xb10 net/bluetooth/l2cap_core.c:794 do_enable_set+0x4ed/0x980 net/bluetooth/6lowpan.c:1082 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Allocated by task 17: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494 kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] l2cap_chan_create+0x40/0x3a0 net/bluetooth/l2cap_core.c:450 chan_create net/bluetooth/6lowpan.c:648 [inline] bt_6lowpan_listen net/bluetooth/6lowpan.c:967 [inline] do_enable_set+0x52f/0x980 net/bluetooth/6lowpan.c:1086 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Freed by task 17: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x103/0x2c0 mm/slab.c:3757 l2cap_chan_destroy net/bluetooth/l2cap_core.c:488 [inline] kref_put include/linux/kref.h:65 [inline] l2cap_chan_put+0x1b2/0x230 net/bluetooth/l2cap_core.c:502 do_enable_set+0x4f9/0x980 net/bluetooth/6lowpan.c:1083 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 The buggy address belongs to the object at ffff888040441000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 32 bytes inside of 2048-byte region [ffff888040441000, ffff888040441800) The buggy address belongs to the page: page:ffffea0001011040 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0002576d48 ffffea0001bec348 ffff8880aa000e00 raw: 0000000000000000 ffff888040441000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888040440f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888040440f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888040441000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888040441080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888040441100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================